In this photo you can see a before and after shot. The one on the right labeled BAD was our first attempt at a fish tank. Even though we used two storage containers they still cracked and leaked all over our studio floor, which was a moist and smelly affair.
The better solution was to use this 100 gallon horse
trough (left image GOOD) from Rubbermaid.
It is strong and food grade and these can be purchased from local horse or cow feed stores for about $82 from Rubbermaid.They also have 150 and 300 gallon tanks if you would like to add more fish to your Farm Fountain. They are made of polyethylene.
Alternatives are to use a bathtub on the interior or plastic liner with a hole dug into the ground for an outdoor system.
In an outdoor system collection of rainwater via a gutter system is a possibility.
Make sure you do not put your fish in chlorinated water as they will die. You can let your water sit out for 24 hours to let the chlorine gasses leave before adding fish.